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Gene Technology
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Genomics - the study of entire genomes
Human genome project
Began in 1990
International effort to sequence the human genome.
2.9 billion DNA base pairs in the human genome
Sequenced and mapped ~25,000 genes
Human Genome Project
• Findings:
– Suprisingly few genes for the large human
genome
– Most DNA is non-coding – does not code for a
protein
– Many genes found in humans are the same as in
other species
– All humans are almost genetically identical
Manipulating genes
• Genetic engineering – moving genes from one organism
into another
• DNA extracted out of cells using a simple chemical
process. Cells are opened and then DNA is separated
from the rest of the cell parts.
Gene manipulation
• Specific sequences of DNA can be excised out of the
genome of organisms.
– Ex. Gene for human insulin
• Restriction enzymes - enzymes that cleave DNA at
specific sequences of nucleotides.
– Cuts it down into more manageable pieces
Restriction enzymes
• Sticky ends - overhang created by some restriction
enzymes cutting in an offset manner.
• Blunt ends - cleavage that leaves DNA cut straight
across.
Recombinant DNA
• Cloning vector - a carrier that
is used to clone a gene and
transfer it from one organism
to another.
• Plasmid – ring of DNA found
in bacterium in addition to its
main chromosome.
Recombinant DNA
• Donor gene - a specific gene isolated from an
organism
– Ex. Insulin gene needed to produce insulin for
diabetes patients
• Recombinant DNA - the combination of DNA from
two or more organisms.
• The donor gene can be placed into an organism to
give it a new characteristic.
• Organisms with recombinant genes may be called
transgenic, recombinant, or genetically modified.
Genetically Modified or Transgenic Organisms
• Genetic engineering is used to create GMOs used in
agriculture, medicine, industry, and basic research.
• Bioremediation – using microbes for environmental
cleanup.
• First GMO was a genetically engineered bacterium
that can digest oil.
Food Crops
• Bacillus thuringiensis (Bt) gene that produces
insecticide is inserted to many crops.
• Transgenic rice with added vitamin A reduced vision
impairment in Asian countries.
• Crops can also be modified to make them easier to
grow and to increase nutrition values.
Livestock
• Livestock engineered to grow faster, more muscle, less
fat, and even more milk with specific proteins in it.
• Some GMOs are sold as unique pets
Medicinal uses
• Gene for insulin is
spliced into cloning
vector and inserted
into a bacterium to
produce needed
protein for diabetes
patients.
• Hemophilia patients
also are treated with
proteins produced this
way.
MRSA
• Due to the excessive use of antibiotics a new bacteria
that is resistant to multiple antibiotics has grown
rampant.
• MRSA is a type of Staphylcoccus aureus that has
developed resistance to penicillin and methicillin, the
two drugs normally used to treat staph infections.
Gene therapy
•Gene therapy – replacing an absent or faulty gene with a
working one.
• Copies of normal
gene are cloned by
bacteria and then
inserted into viruses
or transport vesicles.
• Limited success
because human
body has many
protections against
the invasion and
genetic change that
viruses cause.
• Used to treat cystic
fibrosis today.
These patients have
a defective gene for
an enzyme in
secretory cells.
Stem cells
• Unspecialized cells
that have the
potential to
differentiate.
• Bone marrow cells
give rise to various
blood cells.
Stem Cells
• Cells in new embryos
are able to develop
into any type of cell
except germ cells.
• They can be grown in
tissue cultures.
• Tissues can be reimplanted into a
patient whose tissues
are damaged.
Cloning
• Clone – member of a population of genetically
identical cells produced from a single cell.
– Ex. Asexual reproduction in bacteria, budding in
plants and fungi, and self-fertilization of plants and
animals
• Very few large animals can clone themselves.
• In 1997, Scottish scientist Ian Wilmut announced he
had cloned the first mammal, a sheep named “Dolly”.
Ethical and Social Issues
What do you think about stem cell
research, genetically modified
organisms, and cloning? Should it be allowed? Do the
benefits out way the risks?
More DNA Technologies
• Gel electrophoresis – electric current used to separate
fragments of DNA.
• DNA fingerprint – pattern of bands created by
fragments from an individual’s DNA.
– Used in Forensics to indicate who was at the scene
of a crime.
DNA Fingerprints
Which of the suspects committed the
crime?
A. Suspect 1
B. Suspect 2
C. The boyfriend
D. None of the above
Polymerase Chain Reaction (PCR)
• PCR – process that
replicates DNA
sequences
• Place host DNA, primers,
polymerase, and
nucleotides in a test tube
and control temperature to
start and repeat process
over and over again.
Other DNA Technologies
• Probe – short DNA or RNA strand with attached
radioactive or fluorescent materials to “tag” specific
sequences.
– Nucleotide sequences are complementary to the
gene of interest
• Southern blot – used to indicate certain fragments that
hybridized with a probe.
DNA Sequencing
• The process of determining the exact order of every
nucleotide in a gene.